A METHOD OF HANDLING AT LEAST ONE WORKPIECE IN A WORKSTATION

Abstract

A STATION FOR WORKING ON A WORKPIECE The invention relates to a method of handling at least one workpiece in a workstation for fastening together at least two workpieces, the method being characterized in that it comprises the steps of: • positioning the workpieces in the workstation by means of a support (4); • beginning fastening; • using a handling robot (6) to take over the support function once the fastening has advanced sufficiently to set the relative positioning of the two workpieces; • mounting new workpieces on the support as soon as the handling robot has taken over; and • at the end of fastening together, using the handling robot to remove the workpieces fastened together in this way from the workstation.

Full Text

A STATION FOR WORKING ON A WORKPIECE
The invention relates to a method of handling workpieces in a workstation for fastening together at least two workpieces by an operation such as welding, crimping, riveting, etc.
BACKGROUND OF THE INVENTION
Workstations are known that comprise a support for positioning a workpiece in the workstation while work is being carried out, and a handling robot for removing the workpiece from the workstation once the work has been done. The support is mounted on a slide that enables the support to be extracted from the workstation so as to enable a workpiece to be loaded thereon while a support provided with a workpiece is being introduced into the workstation to enable work to be performed thereon. The loading of a workpiece on the support thus takes place while work is taking place. Nevertheless, that makes it necessary to have at least two supports and a slider system. In addition, the handling robot is not used throughout the duration of a cycle.
OBJECT OF THE INVENTION
It would therefore be advantageous to have means enabling the elements needed for loading and unloading a workpiece in such a workstation to be simplified.
BRIEF DESCRIPTION OF THE INVENTION
To this end, the invention provides a method of handling at least one workpiece in a workstation for fastening at least two workpieces together, the method comprising the steps of:
• positioning the workpieces in the workstation by means of a support;
• beginning fastening;

• using a handling robot to take over the support
function once the fastening has advanced sufficiently to
set the relative positioning of the two workpieces;
■ mounting new workpieces on the support as soon as the handling robot has taken over; and
• at the end of fastening together, using the
handling robot to remove the workpieces fastened together
in this way from the workstation.
Thus, the handling robot is used to a greater extent during the work cycle since it also contributes to positioning the workpiece. Furthermore, the new workpiece can be loaded in the support while work is taking place. In addition, once the workpiece has been taken hold of by the handling robot in order to be positioned, the robot is ready to remove said workpiece once the work has terminated. This saves time in the operation for removing the workpiece.
Preferably, prior to mounting new workpieces on the support, the support is removed from the workstation.
This makes it possible to have a large area available for loading the workpiece on the support without any risk of impeding the movements of the robots that are carrying out the work. Once the new workpiece is on the support, the support can be inserted in the workstation while the preceding workpiece is still being worked on.
Other characteristics and advantages of the invention appear on reading the following description of a particular and non-limiting embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is made to the sole accompanying figure which is a diagram showing a workstation that can be used for implementing the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION
The workstation described herein is a welding station comprising two robots given overall references 1, that are themselves conventional, each having an arm with an end provided with a welding clamp. The welding robots 1 are disposed around a working zone 2 (symbolized by a chain-dotted line).
The workstation includes a loader device 3 for loading workpieces in the work zone 2. The loader device 3 comprises firstly a conventional slider system that enables a support for workpieces for welding together to be introduced into the work zone 2, and secondly a loading robot 5 that places the workpieces on the support 4. The support 4 is movable between a loading position in which the support 4 lies outside the working zone and a working position in which the support 4 is in the working zone. The support 4 also includes in conventional manner members for positioning the workpieces for welding together and for preventing them from moving relative to each other (these members are not shown in the figure).
The workstation also includes a device for unloading the workpiece from the working zone 2, which device comprises a handling robot 6 of conventional kind.
In accordance with the invention, the method of handling begins with a step of loading workpieces on the support 4 while it is in its loading position. The support 4 is then brought into its working position in which it positions the workpieces.
It is then possible to begin welding the workpieces together.
In parallel, the handling robot takes hold of at least one of the workpieces, and once welding has advanced to the point where the relative positioning between the workpieces has become set, the handling robot 6 separates the workpieces from the support 4 and takes over its supporting role. In order to ensure that

welding is not interrupted while the takeover is taking place, the welding robots are programmed to take account of the change in the positioning of the workpieces so as to track the displacement of the workpieces.
The support 4 is then returned to its loading position so that the loading robot 5 can place the following workpieces on the support 4, which is subsequently returned to the working position.
Once welding has been completed, the handling robot 6 removes the workpieces from the working zone, while the welding robots 1 begin to weld together the workpieces that are resting on the support 4.
Thus, the means for positioning the workpieces while work is taking place in the workstation comprise the support 4 for positioning the workpieces during an initial portion -of the work, and the handling robot 6 for positioning the workpieces during a second portion of the work-Naturally, the invention is not restricted to the embodiment described and variants can be applied thereto without going beyond the ambit of the invention as defined by the claims.
In particular, the support 4 can be left in the working zone for loading purposes.
Furthermore, other fastening methods could be envisaged, in particular such as crimping, riveting, stapling, ... .

CLAIMS
1. A method of handling at least one workpiece in a
workstation for fastening together at least two
workpieces, the method being characterized in that it
comprises the steps of:
• positioning the workpieces in the workstation by
means of a support (4);
• beginning fastening;
• using a handling robot (6) to take over the
support function once the fastening has advanced
sufficiently to set the relative positioning of the two
workpieces;
• mounting new workpieces on the support as soon as
the handling robot has taken over; and
• at the end of fastening together, using the
handling robot to remove the workpieces fastened together
in this way from the workstation.
2. A method according to claim 1, characterized in that,
prior to mounting new workpieces on the support (4), the
support is moved out from the workstation.